(Note: some recipes call for mixing the batter in a blender - this pulverizes the gluten and makes the popovers tough, mix the batter as little as possible using a whisk to get the most height out of the finished product).
1 popover pan (the deep tulip shape helps circulate air for tall popovers)
1 and 1/4 cups (not skim) milk (leave the milk out for 30 minutes prior at room temperature)
4 eggs (also at room temperature)
1/2 tsp Mexican vanilla
1 and 1/4 cups flour (use fresh flour, it makes a big difference)
1/2 teaspoon salt
3 Tablespoons butter
Whisk eggs, milk and vanilla in medium sized bowl until light and well mixed.
Mix flour and salt in a small bowl and add to liquids all at once, whisking ONLY until blended. There should still be some small lumps. NOT smooth, NOT big lumps. This is the key. Let the batter sit for at least 15 minutes (you can also make the night before and keep in fridge)
While batter rests, put rack down into bottom third of the oven and preheat oven to 375 F. Remove any rack above your cooking rack as they will rise fairly high. Put popover pan in preheated oven for at least 2 minutes while you melt the butter in the microwave. Remove pan and put a little melted butter into each tin, using a brush to get it up the sides and up over the rim (careful, it's HOT).
Give batter a quick whisk or two and then pour batter in buttered preheated tins about 3/4 full and bake at 375 F for 35 minutes. Makes six. The top will look "done" before the inside is cooked so unless it's burning, leave in for the full 35 minutes.